2021 Transmission Shudder

[Jacksfr]

I have a 2021 Denali HD with the Duramax/Allison combination with about 33k miles and I’m starting to feel a shudder between 45 and 60mph. It completely disappears when I shift into neutral and coast and starts back up as soon as I shift it back into drive. There is no difference with tow/haul mode on or off and seems less noticeable when towing. About 20k mikes are towing a trailer at about 9000 lbs. Dealer has no answers so was wondering if anyone here is/has experienced the same issue and what was the fix. 
 

Thanks 

[elcamino]

I think I would have the trans fluid changed out and I would not put in anything with a GM name on it.  With all the issues related to ATF with the 8sp in the 1500, I would not be surprised if the GM bean counters are at work again cutting corners. 

[GMCustomerService]

13 hours ago, Jacksfr said:

I have a 2021 Denali HD with the Duramax/Allison combination with about 33k miles and I’m starting to feel a shudder between 45 and 60mph. It completely disappears when I shift into neutral and coast and starts back up as soon as I shift it back into drive. There is no difference with tow/haul mode on or off and seems less noticeable when towing. About 20k mikes are towing a trailer at about 9000 lbs. Dealer has no answers so was wondering if anyone here is/has experienced the same issue and what was the fix. 
 

Thanks 

This is certainly not what we like to hear, Jacksfr.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2021 Denali HD. To do so, please send an email to [email protected] with ATTN: Jacksfr/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s privacy policy, please visit https://www.gm.com/privacy-statement.html.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com